In baseball, a double play (denoted as DP in baseball statistics) is the act of making two outs during the same continuous play. Double plays are relatively common, as they can occur any time there is at least one baserunner and less than two outs.

During the 2016Major League Baseball (MLB) regular season, the league average for double plays completed by each team during the course of a 162-game season was 145[1] – nearly one per game by each team.

After stepping on second base, the fielder throws to first to complete a double play

The simplest scenario for a double play is a runner on first base with less than two outs. In that context, four example double plays are:

The batter hits a ground ball

to a middle infielder, who throws the ball to the other middle infielder, who steps on second base to force out the runner coming from first (first out), and then throws the ball to the first baseman in time to force out the batter (second out). As both outs are made by force plays, this is referred to as a "force double play".[2]

to the first baseman, who steps on first base to force out the batter (first out), and with the baserunner trying to advance from first base to second base, throws the ball to the shortstop who tags the runner before he reaches second base (second out). As the force out at first base removed the force condition at second base (requiring that out to be made with a tag), this is referred to as a "reverse force double play".[2]

The batter hits the ball in the air

a line drive to the first baseman, who catches it (first out), and then steps on first base before the baserunner can return to first to tag up (second out). This is also an example of an unassisted double play.

a deep fly ball to the right fielder, who catches it (first out), meanwhile the baserunner tags up and attempts to advance, and the outfielder throws the ball to the shortstop who tags the runner before he reaches second base (second out).

The force double play is the most commonly seen double play, however double plays can occur in many ways in addition to the noted examples, and can involve many combinations of defensive players or even special circumstances (for example, interference).

Per standard baseball positions, the examples given above would be recorded, respectively, as:

4-6-3 (second baseman to shortstop to first baseman) or 6-4-3 (shortstop to second baseman to first baseman)

3-6 (first baseman to shortstop)

3 (first baseman), unassisted

9-6 (right fielder to shortstop)

Double plays that are initiated by a batter hitting a ground ball are recorded in baseball statistics as GIDP (grounded into double play) – this statistic has been tracked since 1933 in the National League and since 1939 in the American League.[3]

Highly desirable to the fielding team and highly undesirable to the batting team, a double play can prove critical to the outcome of a specific game. The fielding team is likely to change pitch selection and defensive alignment to try and get a batter to ground into a force double play. Pitchers may throw pitches more likely to be hit as a ground ball – such as a sinker – while fielders can be positioned to make a ground ball more likely to be turned into a double play. Likewise, the batting team may take action – such as a hit and run play – to reduce the chance of grounding into a force double play.

In baseball slang, making a double play is referred to as "turning two" or a "twin killing". Double plays are also known as "the pitcher's best friend" because they disrupt offense more than any other play, except for the rare triple play. A force double play made on a ground ball hit to the third baseman, who throws to the second baseman, who then throws to the first baseman, is referred to as an "around the horn" double play. A "strike 'em out, throw 'em out" double play occurs when a base runner is caught stealing immediately after the batter strikes out. The ability to "make the pivot" on a force double play – receiving a throw from the third base side, then quickly turning and throwing to first base – is a key skill for a second baseman.

The New York Yankees recorded a rare 4-1-5 double play against the San Francisco Giants on July 24, 2016, in the top of the 8th inning. The Giants had Mac Williamson on first base with one out, when Ramiro Peña hit a ground ball that got by Yankees' first baseman Mark Teixeira but was fielded on the edge of the outfield grass by Starlin Castro. Castro threw to pitcher Chad Green at first base to retire Peña. Meanwhile, Williamson had rounded second on his way to third, and a throw from Green to third baseman Chase Headley resulted in Williamson being tagged out, ending the inning.[7][8]

A bizarre 8-6-2 double play occurred in a nationally televised game between the New York Yankees and Chicago White Sox on August 2, 1985, in the bottom of the 7th inning. With Bobby Meacham on second base and Dale Berra on first base, Rickey Henderson hit a single to deep left-center. Berra ran quickly from first to second, while Meachem stopped his run towards third to return to second base to tag up (expecting the ball would be caught). After the ball was not caught, both runners – now within a few yards of each other – ran to third and then tried to score. A throw from Luis Salazar in centerfield to Ozzie Guillen at shortstop was relayed to catcher Carlton Fisk in time for him to tag out both Meacham and Berra at the plate.[9][10]

A very similar 9-4-2 double play occurred on October 4, 2006, in Game 1 of the NLDS between the Los Angeles Dodgers and the New York Mets. After Russell Martin hit a single to right field, both Jeff Kent and J.D. Drew were tagged out at the plate by catcher Paul Lo Duca.[11][12]

A 9-2-7-2 double play on July 9, 1985, effectively ended the career of Toronto Blue Jays catcher Buck Martinez. With Phil Bradley – a former University of Missouri football player – on second base, Gorman Thomas hit a single to right field. As Bradley rounded third, Blue Jays right fielder Jesse Barfield charged and fielded the ball and threw to Martinez, who had just enough time to catch the ball before absorbing Bradley's full charge. Despite suffering a broken leg and severely dislocated ankle, Martinez maintained control of the ball and registered the out at home plate. As Thomas rounded second, Martinez attempted to throw to third base from a seated position, but the ball missed the third baseman and went into left field. On the error, Thomas rounded third in an attempt to score. Left fielder George Bell fielded the ball near the left-field foul line and quickly returned the ball with a one-hop throw to Martinez, who tagged out Thomas.[13][14][15]

Shifts away from normal defensive alignment can create scenarios in which unusual double plays can occur.

During the April 12, 2008, game between the New York Yankees and the Boston Red Sox, in the top of the 7th inning the Boston infield was shifted right for New York left-handed power hitter Jason Giambi, with a baserunner on first. Giambi grounded to second baseman Dustin Pedroia, who threw to third baseman Kevin Youkilis, covering second due to the shift. Youkilis tagged second, then threw to first baseman Sean Casey to complete the rare 4-5-3 double play.[16]

The Chicago Cubs turned a 7-2-3 double play against the Pittsburgh Pirates on April 2, 2014. Tied 3–3 in the bottom of the 13th inning, the Pirates loaded the bases with no outs. The Cubs then defensively placed left fielder Junior Lake in the infield, near the third base line. Batter Clint Barmes hit a ground ball to Lake, who threw home for one out, and the catcher then threw to first base for the second out.[17][18]